Fluid level sensing assembly and method for configuring same

ABSTRACT

A level sensing assembly senses the level of a fluid in a tank. The tank includes a fluid port that is disposed below the level of the fluid and an air port disposed above the level of fluid. The level sensing assembly includes a lower port in fluid communication with the fluid port of the tank. An upper port is in fluid communication with the lower port of the tank. A measuring vessel is disposed between the lower and upper ports and is in fluid communication therebetween. The measuring vessel includes an auxiliary port disposed adjacent the upper port. The level sensing assembly also includes a level sensor extending down through the auxiliary port into the measuring vessel to measure the level of the fluid in the measuring vessel and the level of the fluid in the tank.

BACKGROUND ART

1. Field of the Invention

The invention relates to level sensing assemblies for measuring thelevel of a fluid in a vessel. More particularly, the invention relatesto a non-float level sensing assembly to measure the level of water in avessel.

2. Background of the Art

There are many situations that require an accurate reading of a fluid ina tank or vessel. While may of these tanks are pressurized, fluid levelmeasurements are also important in non-pressurized tanks. Accurate fluidlevel measurements are important in order to maintain a system operatingas it is designed. Fluid level measurements are important because theycan be used to warn an operator of a system that the fluid in aparticular tank is about to empty. In many situations, the system thatrequires the fluid in the tank may be damaged if the level of the fluidin the tank drops below a certain level.

One example of a system that requires a monitoring of a fluid levelwithin a tank is a boiler system. Steam boilers have feed water controlsthat are responsible for the level of fluid, e.g., water, in the boiler.As the boiler boils the water to create steam, a source of water mustsupply water to the boiler. If the boiler runs out of water, the boilerwill be damaged or destroyed because the steel that creates the boilercannot transfer the thermal energy it receives to the water at a ratesufficient to avoid damage thereto without having a sufficient supply ofwater therewithin.

Referring to FIG. 1, an embodiment of a prior art fluid level sensor isgenerally indicated at 10. The fluid level sensor 10 is in fluidcommunication with a tank 12 that has a fluid 14 therein. The fluid 14defines a fluid level 16.

The fluid level sensor 10 includes a measuring vessel 18 with a waterport 20 and a steam port 22 disposed on either end thereof. A fluidlevel 24, shown in phantom, represents the fluid level 16 in the tank12.

The fluid level sensor 10 includes three separate and independentsystems for measuring the fluid level 24 in the measuring vessel 18. Thefluid level sensor 10 has a mechanical float mechanism, generally shownat 26 that includes a float (not shown) which extends into the measuringvessel 18 to float on the fluid level 24. The fluid level sensor 10 alsoincludes a glass gauge 28 that allows an operator the ability tovisually identify the location of the fluid level 24 within themeasuring vessel 18 without having to open the measuring vessel 18. Thethird mechanism for identifying the fluid level 24 in the measuringvessel 18 includes a set of tricocks 30 that may be opened to identifywhat flows out of each of the set of tricocks 30. The measuring vessel18 includes an auxiliary port 32, which receives a plug 34 therein.

Referring to FIG. 2, the measuring vessel 18 of the prior art is shownprior to installation. The measuring vessel 18 is shipped to a sight forinstallation with the mechanical float mechanism 26 secured thereto(although not shown in FIG. 2 for simplicity). Inserted into theauxiliary port 32 is a temporary plug 36 and a positioning cylinder 38disposed therewithin. The positioning cylinder 38 is coaxial with thetemporary plug 36 and extends down into the interior 40 of the measuringvessel 18. The positioning cylinder 18 is typically fabricated ofcardboard. The positioning cylinder 38 is used exclusively formaintaining the mechanical float in a particular position duringshipment of the measuring vessel 18 to the site of installation. Thepositioning cylinder 38 and temporary plug 36 are removed upon reachingthe site of installation and the auxiliary port 32 is immediatelyplugged with the plug 34 for continued operation of the measuring vessel18 through its life.

The problem with the three mechanisms for identifying the fluid level 24within the measuring vessel 18 is that they are very insensitive and,when translating the mechanical measurement to an electrical signal,inaccurate methods for measuring a fluid level such as the fluid level24. If an operator is not present to view the glass gauge 28, or theglass gauge 28 is dirty or corroded such that the fluid level is notvisible therein, the method of using the set of tricocks 30 or themechanical float mechanism 26 reduces the fluid level sensing assembly10 to one that is very cyclical with the fluid level either being toohigh or too low and rarely being at an optimal level for operation. Thisincreases the costs of energy as more energy is consumed when the levelof fluid in the vessel 12 cycles through such a large range of fluidlevels.

SUMMARY OF THE INVENTION

A level sensing assembly senses the level of a fluid in a tank. The tankincludes a fluid port that is disposed below the level of the fluid andan air port disposed above the level of fluid. The level sensingassembly includes a lower port in fluid communication with the fluidport of the tank. An upper port is in fluid communication with the lowerport of the tank. A measuring vessel is disposed between the lower andupper ports and is in fluid communication therebetween. The measuringvessel includes an auxiliary port disposed adjacent the upper port. Thelevel sensing assembly also includes a level sensor extending downthrough the auxiliary port into the measuring vessel to measure thelevel of the fluid in the measuring vessel and the level of the fluid inthe tank.

BRIEF DESCRIPTION OF THE DRAWINGS

Advantages of the invention will be readily appreciated as the samebecomes better understood by reference to the following detaileddescription when considered in connection with the accompanyingdrawings, wherein:

FIG. 1 is a perspective view, partially cut away, of a fluid levelsensing assembly of the prior art;

FIG. 2 is a perspective view of a measuring vessel of the prior artprior to installation;

FIG. 3 is a perspective view partially cut away of one embodiment of theinvention;

FIG. 4 is a perspective view, partially cut away, of the measuringvessel shown in FIG. 3; and

FIG. 5 is a perspective view, partially cut away, of an alternativeembodiment of the measuring vessel configuration shown in FIG. 3.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring to FIG. 3, one embodiment of the inventive level sensingassembly is generally indicated at 50. The level sensing assembly 50 isoperatively secured to a tank or vessel 52 and senses a level 54 of afluid 56 in the tank 52. The tank 52 is equipped with a fluid port 58and an air port 60. The fluid port 58 creates an opening in the tank 52below the level 54 of the fluid 56. The air port 60 creates an openingin the tank 52 above which the level 54 that the fluid should be. Thefluid 58 and air 60 ports are shown in the upper half of the tank 52. Itshould be appreciated by those skilled in the art that the respectiveports 58, 60 may be positioned anywhere along the tank 52 so long as thefluid port 58 has a portion of the fluid 56 flowing therethrough and theair port 60 is disposed above the position in which the level 54 islocated.

The tank 52 includes a heating element 62, graphically represented as anindentation in the bottom portion of the tank 52. The heating element 62may house a heating element or receive thermal energy from a source toheat up the fluid 56 inside the tank 52 to produce steam for any desiredpurpose. It should be appreciated by those skilled in the art that whilethe inventive level sensing assembly 50 is shown attached to a boilertank 52, the level sensing assembly 50 may be used with any type of tank52, boiler or otherwise, mobile or immobile, pressurized ornon-pressurized. In addition, the tank 52 may be used on a vehicle or ina craft so long as the fluid 58 and air 60 ports maintain their positionrelative to the level 54 of the fluid 56 stored within the tank 52.

As discussed with the prior art, the level sensing assembly 50 includesa lower port 64 that is in fluid communication with the fluid port 58 ofthe tank 52. A pipe 66 extends between the fluid port 58 and the lowerport 64. Likewise, the level sensing assembly 50 includes an upper port68 which is in fluid communication with the air port 60 of the tank 52.A second pipe 70 extends between the upper port 68 and the air port 60.

The level sensing assembly 50 also includes a measuring vessel 72 thatis disposed between the lower 64 and upper 68. The measuring vessel 72provides fluid communication between the upper 68 and lower 64 ports.The measuring vessel 72 also includes an auxiliary port 74 disposedadjacent to the upper port 68. The auxiliary port 74 is threaded andextends through the measuring vessel 72 in an orientation that createsan auxiliary axis 76 which is perpendicular to a plane defined by thelevel 54 of the fluid 56. In the embodiment shown, the auxiliary axis 76created by the auxiliary port 74 is parallel to axes which may definethe upper port 68 and lower port 64.

The measuring vessel 72 includes a glass gauge 78, which is protected bytwo metal rods 80, 82. The glass gauge 78 allows an operator of thelevel sensing assembly 50 to view the level 54 of the fluid 56. Theglass gauge 78 is discussed in greater detail above with reference tothe prior art.

In addition, the level sensing assembly 50 also includes a set oftricocks, generally shown at 84, that also allow an operator tophysically determine the level 54 of the fluid 56.

The level sensing assembly 50 includes a set of tricocks generally shownat 84, that also allow an operator to physically determine the level 54of the fluid 56 in the measuring vessel 72 which corresponds directly tothe level 54 of the fluid 56 in the tank 52. The set of tricocks definea lower 68, middle 80, and upper 90 tricocks and may be used if theoperator were to not be able to use the glass gauge 78. The operator mayopen the upper tricock 90 to determine whether the fluid level was thathigh. If it were not, the operator may open the middle tricock 80 or thelower tricock 86 to identify what flows therefrom.

The level sensing assembly 50 also includes a level sensor 92 thatextends down through the auxiliary port 74 along the auxiliary axis 76into the measuring vessel 72 to measure the level 54 of the fluid 56 inthe measuring vessel 72 and the level of the fluid 56 in the tank 52.The level sensor 92 defines a sensor body 93 that is linear. Morespecifically, the sensor body 93 extends through a straight line.Because the measuring vessel 72 is in fluid communication with the tank52, a portion of the fluid 56 exists in an interior chamber 94 (bestseen in FIG. 4) whereby the portion of fluid 96 disposed therein has alevel 98 which is the same level as the level 54 of the fluid 56 and thetank 52. By measuring the level 98 of the fluid 96 inside the measuringvessel 72, the level sensor 92 can accurately and precisely determinethe level 98 and, hence, the level 54 in the tank 52. The level sensor92 measures the level 98 along its entire length. It can, therefore,identify an infinite number of levels 98 at which the fluid in themeasuring vessel 72 is at. The ability to provide an infinite number ofoutputs allows the control circuit to control the valve feeding fluidinto the tank 52 to open variably to match the rate at which the fluidis leaving the tank 52. This leads to a more even control of the tank 52and less energy consumption when the tank 52 is a boiler. As opposed toan on/off sensor, that only changes its output when the fluid with themeasuring vessel 72 is no longer in contact with the sensor, the levelsensor 92 produces a signal regardless of the level 54 of the fluid 56in the tank 52. And the signal changes with the level 56 of the fluid 54in the tank 52.

In one embodiment, the level sensor 92 is a capacitive sensor that iselectronically connected to a control circuit (not shown) that providesimmediate feedback as to the level 54 in the tank 52. This allows thelevel sensing assembly 50 to minimize the swings (peaks and valleys)between level minimums and level maximums to optimize the energyconsumption of the system by maintaining a level 54 as close to anoptimal level as possible. The capacitive sensor 92 used as the levelsensor 92 is capable of an output that allows greater control than astandard on/off switch. Flow rates can be adjusted based on the level 54of the fluid 56 in the tank 52. This allows the flow of water into thetank 52 to match more precisely the flow of water out of the tank 52 inthe form of steam, avoiding energy absorbing swings in the amounts ofwater being fed into the tank 52. This is because the level sensor 92measures the level 54 in the tank 52 and not merely when the level 54reaches a particular low level, at which point the valve to fill thetank 52 is opened fully allowing a huge amount of cold water into thetank 52, which in turn, requires a greater amount of energy to bring thecold water up to boiling temperature. In the preferred embodiment, thevalve (not shown) is opened an amount proportional to the amount ofwater needed to fill the tank 52 to the optimal level of operation. Ifthe system is slowly having the liquid in the tank 52 exit the system,then the level sensor 92 will indicate such and the valve will not beopened fully. If, on the other hand, the tank 52 is emptying rapidly,the signals produced by the level sensor 92 will indicate such and thevalve will be opened more fully. Therefore, the level sensor 92 assistsin maintaining the level 54 in the tank 52 as close to steady state aspossible.

The level sensor 92 may be any type of sensor that is capable ofextending down into the interior chamber 94 and into the fluid 96 thatis stored therein. Other types of level sensors 92 include, but are notlimited to, resistive and magneto-resistive sensors.

As with the prior art, a cover 100 for a mechanical float mechanism ofthe prior art is shown in FIGS. 3 and 4. By adding the level sensor 92to the auxiliary port 74, much of the mechanical float mechanism thatwas housed within the cover 100 is removed because it is no longernecessary. The cover 100 is, however, typically replaced because it israted as a cover 100 that may close the measuring vessel 72 at the floatport 102. If it were desired, the cover 100 could be replaced with aflat plate, so long as the flat plate were proven to be of a quality ofmetal or material that is acceptable for the rules and regulations thatgovern the safety parameters of these types of vessels. These existprimarily for boilers and pressurized tanks.

As an additional safety feature for the measuring vessel 72, a shut offsensor 104 is included to ensure that the measuring vessel 72 not fail.The shut off sensor 104 is in fluid communication with the fluid 96inside the measuring vessel 72 and will produce a signal which will shutdown any boiler or heating element or pressure generating device that isused in the system to which the tank 52 is attached. The shut off sensor104 is connected to the measuring vessel 72 at a location disposedadjacent the lower tricock 86. More specifically, the lower tricock 86is removed from the measuring vessel and the shut off sensor 104 issecured to the port associated with the lower tricock 86 using aT-shaped pipe 108. Once the shut off sensor 104 is secured to themeasuring vessel 72, the lower tricock 86 is secured to an end of theshut off sensor 104. Therefore, if the fluid 96 within the measuringvalve 72 drops to a level below that which is associated with the lowertricock 86, the shut off sensor 104 will provide a signal to shut downthe system associated with the tank 52 to prevent any damage to the tank52 or the system with which the tank 52 is connected.

The configuration of the level sensing assembly 50 may occur at thepoint in which the measuring vessel 72 is fabricated or, in thealternative, may be configured at a later time after the measuringvessel 72 has been in operation. In other words, the level sensingassembly 50 may be configured as an original manufacturing piece ofequipment. Alternatively, the level sensing assembly 50 may be aretrofit to an existing sensing assembly that may include a mechanicalfloat mechanism 26.

In the situation when the level sensing assembly 50 is originalequipment, the level sensor 92 is secured within the auxiliary port 74along the auxiliary axis 76 at the time of manufacture. In addition, theshut off sensor 104 is secured to the port to which a lower tricock 86would be secured prior to the securing of the lower tricock 86.

In the case of a “retrofit,” the plug 34 that is used to seal theauxiliary port 32 for the fluid level sensing assembly 10 of the priorart is removed. This sometimes requires much effort as the auxiliaryport 32 could have been sealed for decades. Once that is removed, theauxiliary port 74 may be used to receive the level sensor 92 therein.The float mechanism, not shown, that is housed within the cover 100 andwhich also extends down into the interior chamber 94 of the measuringvessel 72 is then removed. The cover 100 could be replaced.Alternatively, an approved plate of material could replace the cover 100as the cover is no longer necessary.

In addition, the lower tricock 86 is removed from the measuring vessel74. A pipe 108 having a “T” configuration is secured thereto. The shutoff sensor 104 is then secured to the pipe 108. The lower tricock 86 isthen secured to a second opening in the pipe 108 that holds the shut offsensor 104 in place. In the preferred embodiment, the pipe 108, tricockport 106 and lower tricock 86 are all pipe threaded to allow each ofthese parts to threadingly engage their respective or adjacent parts.After the shut off sensor 104 and the level sensor 92 are in place, thelevel sensing assembly 50 is sealed by sealing the auxiliary port 74 andthe tricock port 106.

In either method of assembly, either the original equipment or retrofitscenario, the preferred embodiment of the invention has the level sensor92 oriented vertically such that it extends into the fluid 96 within themeasuring vessel 72 perpendicularly to a plane created by the level 98thereof. This avoids any orientation problems associated with possiblyhaving a sensor extend into the measuring vessel 72 at an angle.

Referring to FIG. 5, wherein like primed numerals represent similarelements to those of the preferred embodiment, the level sensor 92′ ismounted within the cover 100′ used to house the float mechanism. As withthe preferred embodiment, the float mechanism is removed. The levelsensor 92′ will operate in a manner identical to the preferredembodiment with the only difference being the signal generation and howit is treated by the control circuitry to match the level 54′ in thetank 52′ based on the location of the level 94′ of the fluid that iscovering the level sensor 52′.

The invention has been described in an illustrative manner. It is to beunderstood that the terminology, which has been used, is intended to bein the nature of words of description rather than of limitation.

Many modifications and variations of the invention are possible in lightof the above teachings. Therefore, within the scope of the appendedclaims, the invention may be practiced other than as specificallydescribed.

1. A level sensing assembly for sensing a level of a fluid in a tankhaving a fluid port disposed below the level of the fluid and an airport disposed above the level of fluid, said level sensing assemblycomprising: a lower port in fluid communication with the fluid port ofthe tank; an upper port in fluid communication with the air port of thetank; a measuring vessel disposed between said lower and upper ports andin fluid communication therebetween, said measuring vessel an auxiliaryport disposed adjacent said upper port; and a level sensor defining asensor body extending down into said measuring vessel to measure thelevel of the fluid in the measuring vessel and the level of the fluid inthe tank by measuring at where along said sensor body the level of thefluid is.
 2. A level sensing assembly as set forth in claim 1 whereinsaid level sensor extends down through said auxiliary port.
 3. A levelsensing assembly as set forth in claim 1 wherein measuring vesselincludes a sensor access port.
 4. A level sensing assembly as set forthin claim 3 wherein said level sensor extends into said measuring vesselthrough said sensor access port.
 5. A level sensing assembly as setforth in claim 2 wherein said sensor body is linear.
 6. A level sensingassembly as set forth in claim 5 wherein said sensor body isperpendicular to the level of the fluid in the tank.
 7. A level sensingassembly as set forth in claim 6 wherein said auxiliary port isthreaded.
 8. A level sensing assembly as set forth in claim 7 whereinsaid level sensor is a capacitive sensor.
 9. A level sensing assembly asset forth in claim 8 wherein said measuring vessel includes a set oftricocks having upper, median and lower drain cocks.
 10. A level sensingassembly as set forth in claim 9 including a shut-off sensor in fluidcommunication with said measuring vessel.
 11. A level sensing assemblyas set forth in claim 10 wherein said shut-off valve is fixedly securedto said lower drain cock.
 12. A method for installing a level sensorinto a measuring vessel having a lower port, an upper port, an auxiliaryport and a set of tricock ports, the method comprising: inserting thelevel sensor into the auxiliary port; orienting the level sensor toextend vertically within the measuring vessel; and securing the levelsensor to the measuring vessel.
 13. A method as set forth in claim 12including the step of installing a shut-off sensor in one of the set oftricock ports.
 14. A method as set forth in claim 13 wherein the step ofsecuring the level sensor includes the step of threadingly engaging thelevel sensor with the auxiliary port of the measuring vessel.
 15. Amethod as set forth in claim 14 including the step of securing levelsensing assembly as set forth in claim 10 wherein said approach lightincludes a light source for emitting visible light therefrom.
 16. Amethod for modifying a level sensing assembly having a measuring vesselwith a lower port, an upper port, an auxiliary port, a set of tricockports and a mechanical float port having a mechanical float extendingtherethrough into the measuring vessel, the method comprising: unsealingthe mechanical float port; removing the mechanical float therefrom;opening the auxiliary port; inserting a level sensor into the auxiliaryport; and sealing the level sensor within the auxiliary port.
 17. Amethod as set forth in claim 16 including the step of orienting thelevel sensor vertically within the measuring vessel.
 18. A method as setforth in claim 17 including the step of orienting the level sensorvertically within the measuring vessel along the entire length thereof.19. A method as set forth in claim 18 including the step of removing atricock from one of the set of tricock ports.
 20. A method as set forthin claim 19 including the step of securing a shut-off sensor to the oneof the set of tricock ports.
 21. A method as set forth in claim 20including the step of securing the tricock to the shut-off valve.
 22. Amethod as set forth in claim 21 wherein the step of removing a tricockincludes removing the tricock from a lower most one of the set oftricock ports.
 23. A method as set forth in claim 22 including the stepof sealing the mechanical float port after the step of removing themechanical float therefrom.